Method of detecting short circuit in water electrolyzer, method of generating hydrogen, and water electrolyzer

Abstract

To make it possible to detect a short circuit in a water electrolyzer even while the water electrolyzer is operating, a voltage sensor is disposed for each of plural water electrolytic cells, the voltage of each of the water electrolytic cells is measured with the voltage sensor while the water electrolyzer is operating, and it is determined that there is a short circuit if it is detected that the voltage is lower than a reference voltage.

What is claimed is: 
     
         1 . A method of detecting a short circuit in plural water electrolytic cells that are put in a water electrolyzer, the method comprising:
 reducing a current density from a stationary current density for water electrolysis;   disposing a voltage sensor for each of the water electrolytic cells, measuring a voltage of each of the water electrolytic cells at the reduced current density with the voltage sensor while the water electrolyzer is operating, and determining that there is a short circuit if it is detected that the voltage is lower than a reference voltage.   
     
     
         2 . A method of detecting a short circuit in plural water electrolytic cells that are put in a water electrolyzer, the method comprising:
 disposing a voltage sensor for every n of the water electrolytic cells, measuring a voltage of the n water electrolytic cells with the voltage sensor while the water electrolyzer is operating, and determining that there is a short circuit if the detected voltage is lower than (n− 1 )Vm+Vb when a stationary voltage for water electrolysis is Vm and a reference voltage is Vb.   
     
     
         3 . A method of generating hydrogen, the method comprising:
 detecting a short circuit according to the method defined in  claim 1  while generating hydrogen with the water electrolyzer.   
     
     
         4 . A water electrolyzer adapted to electrolyze water with a water electrolytic cell to obtain hydrogen, the water electrolyzer comprising:
 plural water electrolytic cells;   voltage sensors provided for the respective water electrolytic cells; and   a controller that obtains voltages from the voltage sensors, wherein   the controller informs that there is a short circuit if any of the voltages obtained while hydrogen is generated with the water electrolytic cells is lower than a reference voltage, and   for detecting a short circuit, the controller periodically reduces a current density to be lower than a current density at a stationary voltage for water electrolysis, to obtain the voltages.